1. Field of the Invention
The present invention relates to a colloidal dispersion and a redispersible composition in the form of a colloidal dispersion, based on cerium oxide.
2. Description of the Related Art Including Information Disclosed under 37 C.F.R. 1.97 and 1.98
Dispersions of cerium compounds are used in numerous applications. There may be mentioned in particular use in heterogeneous catalysis and, especially, catalysis for treatment of exhaust gases from internal combustion engines (catalysis for automobile post-combustion). These dispersions can also be used as an anticorrosion coating agent or in cosmetics.
However, the use of these dispersions is limited by a certain instability over a period of time, leading to sedimentation. Furthermore, the cost of transportation of these dispersions is always increased by the fact that it is necessary to transport, in addition to the active element, the liquid phase in which this is in suspension.
As a result, it is of particular interest to be able to have available either stable dispersions or solid products which are capable of being redispersed to give a colloidal suspension.
In addition, the known processes for the preparation of these dispersions allow only suspensions having a very acid pH, that is to say generally less than 5, to be obtained.
Thus, in the applications which have been mentioned above, and in particular in the case of cosmetics, it is important to be able to have available colloidal dispersions having less acid pH values.
A first object of the invention is therefore the preparation of a stable colloidal dispersion of cerium oxide which has, in particular, a high pH.